A technology is known in the industry which carries out an adjustment of an amount of illumination light by disposing a light control device which includes a turnable light blocking member between a pair of lens arrays (fly-eye lenses) installed inside an illumination device of an image display apparatus such as a projector (see, for example, JP-A-2004-69966). In particular, as this kind of light control device, one is known which uses a pair of opening and closing light blocking bodies which have a shape wherein they are bent like a letter V, and each of which has, for example, a bow-shaped cutout in a leading edge portion (see, for example, JP-A-2009-15295). Also known in the industry are a technology which provides a cutout in an end portion of a block-like light blocking body, and adjusts the amount of blocked light comparatively gently (see, for example, JP-A-2005-17501), and a technology including a diaphragm method which operates four light blocking plates to move in synchronization from four corners so that they come into proximity with, or move away from, each other (see, for example, JP-A-2007-93741).
However, in the case of providing a cutout in the light blocking bodies as in, for example, JP-A-2009-15295, although it is possible to change the amount of blocked light comparatively gently, there is a possibility that at a time of a maximum light blocking rate, that is, when the light blocking bodies are fully closed, light will leak from the cutouts, and the amount of illumination light cannot be sufficiently lowered. In the case of using a block-like light blocking body which has a cutout as the light blocking member, as in JP-A-2005-17501, there is a possibility that it is necessary to form a complex curved surface in an end portion of the light blocking body in order to make the desired change in the amount of blocked light. In this case, a space for the light blocking body is also necessary, but it may be the case that there is a spatial restriction around the pair of lens arrays, and it is difficult to install the block-like light blocking body. Also, in order to operate the four light blocking plates to move in synchronization so that they come into proximity with each other, as in JP-A-2007-93741, it is necessary to provide a complex mechanism.